Why would Crusaders decorate a staircase with the carving of a menorah? This archaeological mystery — almost two millennia in the making — was recently solved, seven years after the Jewish symbol was discovered in a Hebrew University excavation of ancient Tiberias. The massive menorah, originally carved on a basalt tomb door, is tangible evidence of the city’s dramatic historical periods in the past centuries, under the world’s three major monotheistic religions.

The 68×78-centimeter (27×31 inch) seven-stemmed menorah was uncovered in a dig led by the Hebrew University’s Dr. Katya Tzitrin Silverman, which has been ongoing since ...